In a warning to the rest, the Tranmere manager suggests Cook is feeling the benefit on a tough pre-season.
He scored against Woking on Tuesday and the fans’ favourite looked back to the player the supporters know he is.
Mellon now wants him to keep pushing himself – and the Rovers to the top of the league table.
Ahead of tomorrow’s game with Sutton United, the manager said: “Andy has worked really hard in pre-season and he is arguably as fit as he has ever been.
“You can see that with the way that he played - and we have the stats to back that up. He is looking in great shape and he is obviously very determined. He loves scoring goals.
“It was a good goal and we were pleased to see him score.”
But Mellon told the Echo: “I don’t think he was fit enough last year. I don’t think he covered enough grass last year for the jobs that I needed done.
“But he has come back pre-season and he has worked his socks off.
“He is now covering the ground that we want him to cover because it’s important. We have to work with him without the ball. The front men are the first line of defence.”